Method of increasing the output of mechanical roasting furnaces and the like



Feb. 23, 1932.

A. V. CARLSON 1,846,991 METHOD OF INCREASING THE OUTPUT OF MECHANICAL ROASTING FURNACES AND THE LIKE Filed April 9. 1928 4 Sheets-Sheet 1 v gum,

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METHOD OF INCREASING THE OUTPUT OF MECHANICAL ROASTING FURNACES AND THE LIKE Filed April 9, 1928 4 Sheets-Sheet 2 I 4 m a. a

law I Feb. 23, 1932. A. v. CARLSON 3 METHOD OF INCREASING THE OUTPUT 0F MECHANICAL ROASTING FURNACES AND THE LIKE Filed April 9, 1928 4 Sheets-Sheet s J. K ear/sa i v velvfag 1 Feb. 23, 1932.

A. v. CARLSON 1,846,991 METHOD OF INCREASING THE OUTPUT 0F MECHANICAL ROASTING FURNACES AND THE LIKE Filed April 9, 1928 4 Sheets-Sheet 4 Patented Feb. 23. 1932 UNITED STATES PATENT OFFICE,

i ALDEN lTITALIS GABLSON, OF SCHWARTAU, NEAR LUBECK, GERMANY METHOD OF INCREASING THE OUTPUT OI MECEAITIOAI: ROASTING FURNACES THE LIKE Application filed April 9, 1928, Serial No. 268,575, and in Sweden April 25, 1927.

ing-begin and continue. The heat exchange I 10 on the top hearthis here very imperfect as from centrum to periphery and from pethe great layer thickness necessary for a high output and the little heat-conducting power of the charge are hinderin 'so that along influence of the heating ame is requlred. Further the ,intimate contact necessary for a quick and perfect heat exchange between the heating'flame with its hot combustion gases and the charge is wanting. The combustion gases leave the top hearth with a temperature of many hundred degrees without having ignited the charge or in sufiicient degree transmitted heat to the charge or to furnacewalls or hearths. The insufficient heating of the charge reached on the first hearth is increased on the following hearths by means of the hot roasting gases. For the most the reaction tem erature for the intended process rst on the third or fourth hearth.

is reached The transport of the charge in the different hearths generally takes place alternately riphery to centrum by means of a central shaft, the motion velocity of which is dependent on and adjusted according to the reaction velocity of the charge in its turn dependent on the quickness with whichthe charge can be heated and ignited. Against an increased output through the increased motion velocity of the central shaft there stand anunfavourable roasting-effect and a bad heat exchange.

This invention effects that the output of the furnace is essential y increasedmore than 40% higher output has been obtained at durable output on working scale- -that through the suitable arrangement of the heatin flame a more perfect heat exchange is reached and fuel up to 40% spared and that the working of the furnace becomes simpler and the roasting essentially better. These advantages are reached thereby that the heating flame is at the combustion pressed on to the charge and ignites the sulphur therein, and that the hot exhaust gases from the top hearth are not, as before, conducted directly to an outlet but are blown into the grooves formed in the charge at the transport and then forced to .pass chambers or channels through which the charge .is conducted to the furnace.

Through a suitable arrangement of burners or a system of burners the exhaustgases for reaching a rational heat exchange and ignition of the sulphur are caused to .pass over the charge and after circulatory movement be sucked into the dryin and heating apparatus. At the combustlon the fuel currentoil, gas and coaldustis conducted tangentially into the furnace by an annularly surrounding air-current, I and passes over the transport grooves and shoulders situated next to the furnace wall. The current is directed obliquely downwards and along the charge so that a combustion flame is formed passing over the transportgrooves and shoulders. By introducing the fuel current in this manner in one place or with in rotary respect the same direction in several places in the furnace the flame and the exhaust gases obtain a circulatory movement gradually moving against the outlet situated in the middle I of the furnace-arch. By this there will be on the top hearth high temperature difl'erences between the combustion gases and the charge, and owing to that a very complete heat exchange will take place. Simultaneously, by the intimate contact of the heating flame with thedried and. pre-heated' charge the combustible sulphur therein is ignited and through the continuous stirring of the charge at the transport the combustion of the sulphur spreads quickly all through the charge. On the top hearth. it is to ignite the combustible sulphur in the charge quickly. In order to realize that what is intended, it is necessary that the charge is dry and heated and that it is passed over by the combustion flame and the exhaust gases. To maintain the charge at the reaction temperature or give it temperatures above the reaction temperature or to increase the reaction cal section of theupper portion of a roasting.

velocity burners may be disposed even on the other furnace hearths. lPreheated air, if desired also steam in small quantities, may suitably be blown in either at the combustion or for hastening the reaction.

In the means for drying and-pre-heating,

which may be disposed within. or outside the output and the better utilization. of the heat-- ing flame entail very considerable technical and economical advantages.

The'bringing of the exhaust gases into intimate contact with the charge while pass ing through the same may be performed in different manners according to the sort and the physical properties of the charge. In an extension on or in the furnace one can let the charge fall down in steps while the exhaust gases passing through and against the same. One can also lead the exhaust gases through a rotating drum, through which the charge is conducted in such a manner that it falls from the top.downward in the drum at the rotation, or lead the charge forward through screws, stirring devices or the like in a closed chamber, through which the exhaust gases from the furnace are led.

Figure 1 is a side elevation, partly in vertifurnace.

gases through a rotating drum e. Figures and 8 show a closed feeding chamber f, through which the material is conducted by means of a rotating transport device under pre-heating through influence of the exhaust gases.

Having now described my invention, what I claim as new and desire to secure by Letters Patent is: I

A method of operating mechanical roasting furnaces, wherein a combustion of supplied fuel and the contents of the material takes place during formation of flue gases which are led away, and wherein the charge of material into the furnace is carried in a direction in opposition to the flow of the gases of combustion and the material is repeatedly caused to fall freely in the current of passing gases to subject the material to intimate and prolonged action of the gases to preheat the material before it is subjected to reaction temperature, the fuel being admitted to the furnace in a tangential current pointed obliquely downwardly and passing directly over the material introduced into the furnace.

In witness whereof, I have hereunto signed my name.

ALBIN VITALIS QARLSON.

Fig. 2 is a, sectional view on line 2-2 of- Fig.

Fig. 3 is a vertical section through the upper part'of the furnace.

Fig. 4 is a sectional view on line 44 of Fig.

Fig. 5 is a vertical sectional view of a modified form of the invention, the rotary drumthese plates the charge is fed under influence of skimmers d. In the modification according to Figures 5 and 6 the material is conducted in counter-current against the exhaust 

